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IC 9257 



BUREAU OF MINES 
INFORMATION CIRCULAR/1990 

D300 
j7 



International Intercalibration and 
Intercomparison Program Radon 
Daughter Measurements 

Exercise at the Twilight Mine, Uravan, CO 
By W. E. Cooper and R. F. Holub 







U.S. BUREAU OF MINES 
1910-1990 



V YEARS a THE MINERALS SOURCE 



Mission: As the Nation's principal conservation 
agency, the Department of the Interior has respon- 
sibility for most of our nationally-owned public 
lands and natural and cultural resources. This 
includes fostering wise use of our land and water 
resources, protecting our fish and wildlife, pre- 
serving the environmental and cultural values of 
our national parks and historical places, and pro- 
viding for the enjoyment of life through outdoor 
recreation. The Department assesses our energy 
and mineral resources and works to assure that 
their development is in the best interests of all 
our people. The Department also promotes the 
goals of the Take Pride in America campaign by 
encouraging stewardship and citizen responsibil- 
ity for the public lands and promoting citizen par- 
ticipation in their care. The Department also has 
a major responsibility for American Indian reser- 
vation communities and for people who live in 
Island Territories under U.S. Administration. 



Information Circular 9257 



International Intercalibration and 
Intercomparison Program Radon 
Daughter Measurements 

Exercise at the Twilight Mine, Uravan, CO 
By W. E. Cooper and R. F. Holub 



UNITED STATES DEPARTMENT OF THE INTERIOR 
Manuel Lujan, Jr., Secretary 

BUREAU OF MINES 
T S Ary, Director 



$ A 




Library of Congress Cataloging in Publication Data: 



Cooper, W. E. (Wade Emanuel), 1955- 

International intercalibration and intercomparison program radon daughter 
measurements. Exercise at the Twilight Mine, Uravan, CO / by W. E. Cooper and 
Robert F. Holub. 

p. cm. - (Bureau of Mines information circular; 9257) 

Includes bibliographical references. 

Supt. of Docs, no.: I 28.27:9257. 

1. Mine gases-Colorado-Twilight Mine-Measurement. 2. Radon-Isotopes- 
Measurement. I. Holub, Robert F. II. Title. III. Series: Information circular 
(United States. Bureau of Mines); 9257. 

TN295.U4 [TN305] 622 s-dc20 [622'.82] 90-1743 

CIP 



CONTENTS 

Page 

Abstract 1 

Introduction 2 

Acknowledgments 2 

Measurement facilities and procedures 2 

Results and discussion 5 

Conclusions 12 

References 12 

Appendix-Participants 13 

ILLUSTRATIONS 

1. Plan map of the Twilight Mine 4 

2. Total radon daughters, radon, barometric pressure, and relative humidity as functions of time, 

September 12, 1988 9 

3. Total radon daughters, radon, barometric pressure, and relative humidity as functions of time, 

September 13, 1988 10 

4. Total radon daughters, radon, barometric pressure, and relative humidity as functions of time, 

September 14, 1988 11 

TABLES 

1. Participants 3 

2. Participant equipment and procedures 3 

3. Radon daughter concentrations 6 

4. Working level concentrations 7 

5. Ratio of reported working levels over average working levels 8 

6. Ratio of calculated working levels using reported radon daughter concentrations over reported 

working levels 8 

7. Ratios of flow-corrected working levels over average working levels 12 



UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 


cm/s 


centimeter per second 


MeV 


million electron volt 


ft 


foot 


min 


minute 


h 


hour 


mm 


millimeter 


hp 


horsepower 


fim 


micrometer 


kBq/m 3 


kilobecquerel per cubic meter 


pCi/L 


picocurie per hter 


kPa 


kilopascal 


WL 


working level 


L/min 


hter per minute 







INTERNATIONAL INTERCALIBRATION AND INTERCOMPARISON 
PROGRAM RADON DAUGHTER MEASUREMENTS 

Exercise at the Twilight Mine, Uravan, CO 
By W. E. Cooper 1 and R. F. Holub 2 



ABSTRACT 

The International Inter calibration and Intercomparison Program (HIP), consisting of several selected 
laboratories from four countries, held a radon progeny intercomparison measurement at the U.S. Bureau 
of Mines experimental Twilight Mine on September 12-14, 1988. Grab samples were taken at four 
different conditions of low and high radon progeny and condensation nuclei concentrations, respectively. 
The results showed good agreement among all seven participants. The coefficient of variation of all 
measurements was 4.7%; after minor corrections for flows and some systematic biases, it was reduced 
to 3.2%. 



fining engineer, U.S. Mine Safety and Health Administration, Department of Labor, Denver, CO. 
2 Physicist, Denver Research Center, U.S. Bureau of Mines, Denver, CO. 



INTRODUCTION 



The accurate assessment of both occupational and gen- 
eral public exposure to radon and radon daughters is de- 
sirable to estimate their associated carcinogenic risk. For 
accurate exposure assessment, it is necessary to quantita- 
tively evaluate the accuracy of different methods and 
equipment used to measure radon and radon daughter 
concentrations. In 1983, the Committee on Radiation 
Protection and Public Health (CRPPH) of the Organiza- 
tion for Economic Cooperation and Development, Nuclear 
Energy Agency (OECD/NEA) recognized this necessity 
and decided to set up an international program of inter- 
calibration and intercomparison of equipment and tech- 
niques used for the monitoring of radon, thoron, and their 
short-lived daughters. From the beginning, this program 
was merged with a similar program conducted by the 
Commission of the European Communities (CEC). The 
primary purpose of the program was to quantitatively 



assess measurement differences among international lab- 
oratories or groups to provide a forum for alleviating or 
reducing differences and inaccuracies. Because of the 
importance of accurate radon measurements in mining 
health and safety, the U.S. Bureau of Mines was one of the 
participating organizations from the United States. 

The program was initially divided into three parts: 
intercalibration and intercomparison of radon measure- 
ments, intercalibration and intercomparison of radon 
daughter measurements (laboratory environment), and 
intercomparison of radon daughter measurements in real 
mine and dwelling conditions. The first two parts of the 
program have been completed and the results reported 
(7-2). 3 This report summarizes the results of one of sev- 
eral intercomparisons performed at mines and dwellings 
that will be included in the report on the third part of the 
program. 



ACKNOWLEDGMENTS 



The authors acknowledge the assistance of T. H. Davis, 
electronics technician, and R. F. Droullard, geophysicist, 
both of the Denver Research Center, in preparing the 



mine, in performing the continuous measurements, and in 
organizing this exercise. 



MEASUREMENT FACILITIES AND PROCEDURES 



Radon daughter grab sample measurements for this in- 
tercomparison were taken in the controlled mine atmo- 
sphere of the Bureau's Twilight Mine, located about 10 
miles northwest of Uravan, CO. The mine is a previously 
operating uranium-vanadium mine, which was acquired by 
the Bureau to conduct in-house and contract research. 
The ore zone consists of a well-sorted, fine-grained, highly 
fractured sandstone with abundant carbonaceous material. 
A plan view map of the mine configuration and facilities is 
included as figure 1. The mine and its facilities are de- 
scribed in detail elsewhere (3). The measurements were 
done in the air-cleaning test area shown in figure 1. 

The ventilation system of the mine consists of twin 20- 
hp primary fans (back to back) located at the main exhaust 
portal (portal B) and a two-stage, 7-1/2-hp each, second- 
ary fan located at bulkhead B of the North Loop (fig. 1). 
The secondary fan automatically turns on in the event of 
power failure. The primary fan ran continuously through- 
out the intercomparison, while the secondary fan was used 
only as needed to provide recirculation around the North 
Loop, thereby increasing radon daughter concentrations 
in the measurement area. A small diesel engine was sit- 
uated at drift IL5 and used as required to entrain diesel 



pollutants into the mine air. Throughout the intercom- 
parison, continuous measurements of radon, radon daugh- 
ters, barometric pressure, and relative humidity were taken 
to evaluate factors that may affect radon daughter concen- 
trations. All of these measurements, except barometric 
pressure, were taken in the measurement area shown in 
figure 1. Barometric pressure was measured outside the 
mine near the instrument trailer. Details about the mon- 
itoring equipment are given in reference 3. 

The intercomparison participants and their equipment 
and procedures are listed in tables 1 and 2. Grab samples 
were taken under four conditions: 

1. Low radon daughter concentration (0.22 to 0.50 WL) 
with no diesel pollutants; 

2. Low radon daughter concentration (0.31 to 0.33 WL) 
with diesel pollutants; 

3. High radon daughter concentration (0.86 to 0.94 
WL) with no diesel pollutants; 



Italic numbers in parentheses refer to items in the list of references 
preceding the appendix. 



4. High radon daughter concentration (0.73 to 0.92 
WL) with diesel pollutants. 

The ranges of radon daughter concentrations presented are 
the ranges of the average concentration obtained by the 
participants. The participants' filter holders were posi- 
tioned near the middle of the mine airway with the filter 
faces directed toward the mine airflow. Mine air velocities 
(about 50 cm/s) in the measurement area were higher 
than the pump flow rate air velocities at the filter face. 
The filter holders were kept within a few centimeters of 
each other to help minimize effects due to measurement 
of different air. 



Table 1 .-Participants 1 

Abbreviation 

Atomic Energy Control Board AECB 

Australian Radiation Laboratory ARL 

Environmental Measurements Laboratory, 

U.S. Department of Energy EML 

Department of Energy, Mines, and 

Resources, CANMET EMR 

Mine Safety and Health Administration, 

U.S. Department of Labor MSHA 

Bureau of Mines, U.S. Department of the 

Interior USBM 

University of Salzbu rg U.S. 

l See appendix for more detailed listing. 



Table 2.-Participant equipment and procedures 





Detector 


Counter 
efficiency 




Filter 




Pump 

flow rate, 

L/min 




Participant 


Type 


Manufacturer 


Type 


Diam, 
mm 


Pore 
size, /xm 


Method 


AECB . . . 


ZnS Trimet. 


NURAD . . . 


0.435 
.440 


Mi Hi pore 
membrane 
AA. 


25 


0.8 


3.70 
3.80 


5-min modified 
Tsivoglou. 


ARL 


ZnS drawer 
assembly. 


ARL 


.444 


Gelman 
membrane 
GA-4. 


25 


.8 


6.12 


Do. 


EMI 


ZnS Th-29-B 
TD-19. 


ELM 


.470 


Reeve angel 
glass fiber, 
934AH. 


50 


NAp 


3.20 


Do. 


EMR . . . 


ZnS Trimet. 


NURAD . . . 


.467 


Millipore 
membrane 
AA. 


25 


.8 


3.63 


Do. 


MSHA . . 


ZnS radon- 
flask 
detector. 


Ludlum . . . 


u .440 
3 .476 

4 .488 


Gelman glass 
fiber A/E. 

Millipore 
membrane 
AA. 


25 
25 


NAp 
.8 


4.47 
3.94 

3.92 


Do. 


USBM . . 


. . do. . . . 


. . do 


.477 


. . do 


25 


.8 


2.80 


Do. 


U.S 


Silicon- 
diode. 


Pylon 


.20 


Pylon 


25 


NAp 


6.00 


Alpha-spectroscopy 
(RaA-RaC). 



NAp Not applicable. 

1 Hlter self-absorption included. 

2 Sept. 12, 1988. 

3 Sept. 13, 1988. 

4 Sept. 14, 1988. 

NOTE.-Reference to specific products does not imply endorsement by the U.S. Bureau of Mines. 



IRI Power center 

IR2 Golf - cart charging system 

ILI Protective clothing orea 

IL2 Storage area 

I L3 Charging center 



Site 

IR3 

IR5 

IR5-I 

IR5-2 

IR6 

IR7 

IR8 

IL4 

IL5 

IL6 

IL6-I 

IL6-2 

IL7 

IL8 

IL9 

ILIO 



2RI 
2R2 
2R3 
2R4 
2R5 
2R6 



3RI 

3R2 

3R3 

3R4 

3LI 

3L2 

3L2-I 

3L2-2 

3L2-3 

3L2-4 

3L3 

3L4 

3L5 

3L6 

3L6-I 

3L6-2 

3L6-3 

3L6-4 

3L6-5 

3L6-6 

3L7 



Width, 
ft 

10 

10 
10 
8 
10 
10 
15 
20 

10 
20 
30 
30 

15 
10 



10 
10 
10 
20 
10 

10 
10 
10 
10 



20 
20 

10 
10 
10 
10 
20 



Length, 
ft 
25 

25 
30 
40 
25 
55 
50 
50 

20 
20 
65 
25 



35 
7 
25 
27 
35 
55 



15 
5 

5 
15 
5 

5 

30 
15 

5 
35 
115 
20 



10 
35 
30 
30 
10 
20 




Instrument trailer 



3] Office 



Figure 1.-Plan map of the Twilight Mine. North Loop is defined by bulkheads A and B. 



RESULTS AND DISCUSSION 



The results of the continuous measurements of radon, 
radon daughters, barometric pressure, and relative hu- 
midity are presented in figures 2-4. Also shown on these 
figures are the time periods for which the diesel engine 
was operating and the bulkhead B secondary fan (North 
Loop fan) was on. The relative humidity was high (60% 
to 70%) on September 12, 1988, because of rain occurring 
outside the mine. The continuous radon daughter con- 
centration measurements lag behind the radon concen- 
tration measurements about 1 h because of the detection 
methods utilized. As expected, the ratio of the radon 
daughter concentration over the radon concentration in- 
creased with the entrainment of diesel pollutants. These 
figures also show that barometric pressure inversely af- 
fected the radon concentration, as reported previously (4). 

The reported results of the individual radon daughter 
concentration measurements for three consecutive days 
are presented in table 3. Also included are the calculated 
average concentration and coefficient of variation for each 
sample time. These results showed average coefficients of 
variation of 13%, 10%, and 15%, respectively, for RaA, 
RaB, and RaC at low concentrations (0.22 to 0.50 WL). 
These low concentration results corresponded to average 
concentrations of 89, 33, and 22 pCi/L, respectively, for 
RaA, RaB, and RaC. At high concentrations (0.73 to 
0.94 WL), September 14, the results corresponded to av- 
erage concentrations of 170, 91, and 64 pCi/L and coef- 
ficients of variation of 11%, 6.7%, and 8.2%, respectively, 
for RaA, RaB, and RaC. Lower coefficients of variation 
at the high concentrations were expected because of a 
reduction in the statistical counting uncertainty. 

The reported radon daughter concentrations are pre- 
sented in table 4. Also listed in the table are the average 
concentrations for each sample time and the coefficients of 
variation for the sampling results at each time. The coef- 
ficients of variation ranged from 11.4% to 2.1%, with an 
overall average coefficient of variation of 6.0%. 

The reported radon daughter sampling results for each 
of the participants was analyzed further by calculating the 
ratio of the reported working level concentration and the 
average concentration for each sample time. These cal- 
culated results, along with the average ratio and standard 
deviation for each participant, are listed in table 5. The 
average ratio provides an indication of the average percent 
that the participants' results were above or below the 
average concentration. The results showed an average 
ratio range of 0.957 to 1.046. The standard deviation 
provides an indication of the variability of the participants' 
sampling results. Some uncertainty in determining the 
actual working level would also be included in the listed 
standard deviations because the average concentration 
was used to estimate the actual working level. The av- 
erage standard deviation for the participants (the last 
column in table 5) was only 4.7%. This low standard 



deviation indicates that the measurement uncertainty for 
each of the participants was relatively constant. It also 
indicates that the differences in average ratio among the 
participants are probably largely due to systematic bias. 

The amount of systematic bias due to computational 
differences in converting individual radon daughter con- 
centrations to working levels was analyzed by converting all 
of the reported individual daughter concentrations to work- 
ing levels using a constant conversion factor and com- 
paring these results with the reported working level con- 
centrations. The ratio of the calculated working level and 
the reported working level was computed and the average 
ratio for each participant determined. The results of these 
calculations are presented in table 6. 

From the table 6 results, the Environmental Measure- 
ments Laboratory (EML) and the Mine Safety and Health 
Administration (MSHA) showed some systematic bias 
when converting individual radon daughter concentrations 
to working levels. These systematic biases were calculated 
at about 1% for EML and 2% for MSHA. The bias for 
MSHA resulted from using a conversion factor of 1.28E5 
MeV = 1 WL instead of 1.3E5 MeV = 1 WL. For EML, 
the indicated bias is probably due to two factors: (1) the 
use of half- lives of 3.11 min and 19.9 min, respectively, for 
RaA and RaC instead of 3.05 min and 19.7 min, and (2) 
reporting the individual radon daughter concentrations to 
only two significant digits, while the other participants 
reported their results to three significant digits. The lower 
number of significant digits resulted in a higher standard 
deviation for the ratio than those obtained for the other 
participants. This higher standard deviation would result 
in a higher uncertainty for EML's average ratio. These 
estimated systematic biases should result in their measure- 
ments being above the average results by the appropriate 
percentages. 

It was noticed that the Department of Energy, Mines, 
and Resources (EMR), MSHA, and the Atomic Energy 
Control Board (AECB) used the same pump calibration 
device at the minesite and all three participants' results 
were above the average. This prompted a further analysis 
of their pump calibration device in the laboratory. The 
pump calibration device used was a Gilibrator, similar to 
the Buck Calibrator recently tested by MSHA (5). The 
Buck Calibrator showed a systematic bias of 1.4% at a 
flow rate of about 2.0 L/min (5). A laboratory compari- 
son of the Gilibrator against a Brooks flowmeter at 4.0 
L/min showed a systematic bias of about 2.5%. This 
indicates that the results of the three participants are 
probably systematically biased about 2.5% high because of 
an inaccurate pump flow rate calibration at the time of the 
intercomparison. However, as was apparent during the 
last intercomparison in France, in June 1989, the problem 
of measuring flow has not been satisfactorily resolved. 



Table 3.-Radon daughter concentrations, picocuries per liter 



Date and 
participant 
Sept. 12, 1988: 

AECB 

ARL 

EML 

EMR 

MSHA 

USBM 

Average 

COV % . . 

Sept. 13, 1988: 

AECB 

ARL 

EML 

EMR 

MSHA 

USBM 

Average 

COV % . . 

AECB 

ARL 

EML 

EMR 

MSHA 

USBM 

Average 

COV % . . 

AECB 

ARL 

EML 

EMR 

MSHA 

USBM 

Average 

COV % . . 

See notes at end of table 



Time: 14:01 



Time: 15:15 



Time: 16:09 



RaA 


RaB 


RaC 


RaA 


RaB 


RaC 


RaA 


RaB 


RaC 


95.7 


35.7 


17.6 


111.3 


32.1 


13.9 


82.2 


31.4 


21.8 


84.9 


32.1 


22.9 


105.4 


29.8 


16.5 


88.6 


34.9 


17.8 


NA 


NA 


NA 


89.1 


30.2 


17.0 


81.0 


31.6 


22.1 


NA 


NA 


NA 


NA 


NA 


NA 


NA 


NA 


NA 


69.3 


31.1 


22.8 


83.6 


27.7 


18.9 


78.2 


30.5 


20.4 


74.7 


26.4 


26.2 


93.7 


28.6 


16.2 


94.5 


34.3 


14.8 



81.15 
14.4 


31.33 
12.2 


22.38 
15.9 


96.61 29.70 
11.9 5.7 


16.51 
10.8 


84.90 
7.8 


32.54 
6.0 


19.39 
15.9 




Time: 9:00 




Time: 10:00 






Time: 11:00 




RaA 


RaB 


RaC 


RaA RaB 


RaC 


RaA 


RaB 


RaC 



NA 
60.1 

NA 
61.7 
79.9 

NA 



77.6 
72.0 
56.7 
103.7 
88.4 
69.7 



78.2 
20.9 



RaA 



143.0 
148.0 
121.5 
169.6 
157.1 
137.9 



146.18 
11.3 



NA 
18.6 

NA 
22.5 
22.6 

NA 



NA 
16.2 

NA 
15.8 
17.3 

NA 



51.6 
62.3 
62.1 
57.2 
46.8 
60.3 



19.2 
22.3 
20.0 
24.8 
18.7 
17.9 



20.0 
13.0 
13.0 
15.6 
22.3 
12.6 



68.4 
84.9 
72.9 
99.3 
79.9 
70.8 



32.0 
38.7 
37.8 
40.3 
40.9 
34.5 



36.2 
25.5 
27.5 
38.3 
37.2 
29.8 



21.1 
19.4 
28.4 
21.2 
24.2 
23.6 



96.5 28.1 

86.7 30.1 

72.9 29.4 

116.2 30.0 

78.5 21.5 



81.3 



32.8 



20.5 
17.8 
17.8 
18.8 
26.5 
16.1 



112.9 
121.0 
108.0 
102.4 
108.9 
124.0 



40.4 
35.6 
38.6 
43.9 
37.6 
37.0 



32.42 
16.9 



22.97 
13.8 



88.68 
17.7 



28.66 
13.3 



19.59 
18.8 



112.87 
7.3 



37.36 
5.4 



Time: 15:00 



Time: 16:00 



RaB 



RaC 



RaA 



RaB 



RaC 



52.4 
45.4 
43.2 
54.5 
50.6 
45.7 



26.8 
28.5 
27.0 
25.2 
31.8 
33.2 



112.9 
114.0 
116.1 
144.8 
107.2 
124.6 



41.7 
39.1 
45.9 
51.8 
42.7 
43.7 



29.7 
28.8 
21.6 
26.8 
31.8 
29.8 



48.64 
9.3 



28.76 
10.8 



119.94 
11.2 



44.15 
9.9 



28.08 
12.7 



31.3 
24.9 
24.3 
22.4 
31.4 
26.4 



67.23 
16.4 


21.23 
10.7 


16.43 
4.7 


56.71 20.48 
11.1 12.7 


16.08 
25.7 


79.37 
14.5 


37.37 
9.2 


26.79 
14.1 




Time: 12:00 




Time: 13:00 






Time: 14:00 




RaA 


RaB 


RaC 


RaA RaB 


RaC 


RaA 


RaB 


RaC 



23.6 
21.4 
18.4 
27.7 
27.4 
20.5 



23.16 
16.4 



Table 3.-Radon daughter concentrations, plcocurles per liter-Continued 



Date and 

participant 

Sept. 14, 1988: 

AECB 

ARL 

EML 

EMR 

MSHA 

USBM 

Average 

COV % . . 

AECB 

ARL 

EML 

EMR 

MSHA 

USBM 

Average 

COV % . . 

AECB 

ARL 

EML 

EMR 

MSHA 

USBM 

Average 

COV % . . 

COV Coefficient of variation. 
NA Not available. 



Time: 9:00 



Time: 10:00 



Time: 11:00 



RaA 



RaB 



RaC 



RaA 



RaB 



RaC 



RaA 



RaB 



RaC 



153.2 
155.0 
126.9 
155.5 
136.3 
116.2 



184.1 
153.0 
170.1 
156.5 
181.3 
169.1 



169.02 
7.5 



RaA 



201.7 
NA 
180.9 
238.5 
226.8 
197.2 



209.02 
11.1 



89.0 
82.1 
72.9 
81.5 
77.4 
68.2 



61.5 
54.5 
54.0 
51.7 
54.9 
51.6 



183.1 
159.0 
132.3 
144.4 
171.0 
147.9 



97.0 
89.5 
81.0 
86.0 
89.1 
84.8 



62.0 
56.6 
62.1 
62.6 
64.3 
66.2 



177.5 
169.0 
129.6 
172.4 
179.5 
158.2 



100.1 
96.5 
83.7 
94.3 
91.5 
88.7 



111.2 
96.3 
91.8 
96.1 
90.7 
99.8 



70.5 
68.9 
62.1 
67.5 
70.9 
68.5 



182.7 
159.0 
170.1 
198.8 
199.6 
172.6 



104.8 
97.6 
91.8 
98.6 
93.3 
92.8 



73.5 
68.1 
59.4 
64.4 
73.5 
72.1 



146.1 
NA 
191.7 
189.3 
171.8 
149.8 



97.66 
7.6 



68.07 
4.7 



180.47 
9.1 



96.48 
5.1 



68.50 
8.3 



169.74 
12.6 



Time: 14.59 



RaB 



RaC 



103.6 

NA 

91.8 

103.7 
90.8 
93.3 



63.2 
NA 
56.7 
56.1 
64.3 
65.6 



96.63 
6.7 



61.19 
7.3 



88.9 
NA 
94.5 
93.3 
85.9 
83.6 



89.23 
5.2 



69.0 
59.9 
70.2 
62.5 
71.3 
72.3 



140.52 
11.9 


78.52 
9.4 


54.70 
6.6 


156.28 87.90 
11.9 6.2 


62.30 
5.2 


164.37 
11.3 


92.47 
6.3 


67.53 
7.5 




Time: 12:00 




Time: 13:00 






Time: 14:01 




RaA 


RaB 


RaC 


RaA RaB 


RaC 


RaA 


RaB 


RaC 



81.7 
NA 
51.3 
55.9 
76.4 
66.4 



66.35 
19.6 



Table 4. -Working level concentrations 



Participant 



Sept. 12, 1988 



Sept. 13, 1988 









14:00 


15:15 


16:09 


9:00 


10:00 


11:00 


12:00 


13:00 


14:00 


15:00 


16:00 


AECB 






0.345 


0.329 


0.325 


NA 


0.225 


0.350 


0.341 


0.318 


0.409 


0.513 


0.438 


ARL . 






.337 


.323 


.336 


0.218 


.227 


.378 


.277 


.310 


.388 


.492 


.425 


EML. 






NA 


.313 


.329 


NA 


.215 


.357 


.307 


.295 


.380 


.454 


.442 


EMR 






NA 


NA 


NA 


.238 


.244 


.392 


.382 


.344 


.388 


.548 


.515 


MSHA 






.325 


.308 


.317 


.265 


.230 


.414 


.376 


.293 


.412 


.546 


.453 


USBM 






.309 


.304 


.329 


NA 


.202 


.346 


.311 


.310 


.392 


.497 


.461 


U.S. . , 


fle . 




NA 


NA 


NA 


NA 


NA 


.361 


.329 


.290 


.355 


.482 


.449 


Avera 


.329 


.315 


.327 


.240 


.224 


.371 


.332 


.309 


.389 


.505 


.455 


SD . 






.016 


.010 


.007 


.024 


.014 


.025 


.038 


.019 


.019 


.034 


.029 


COV 




. % . . 


4.8 


3.3 


2.1 


9.8 


6.4 


6.7 


11.4 


6.1 


4.9 


6.7 


6.4 








Sept 


. 14, 1988 
















9:00 


10:00 


11:00 


12:00 


13:00 


14:01 


14:59 




AECB 






0.838 


0.911 


0.947 


1.016 


0.993 


0.906 


0.968 










ARL . 






.781 


.832 


.890 


.905 


.915 


.856 


.875 










EML . 






.721 


.780 


.831 


.887 


.879 


.864 


.879 










EMR 






.769 


.821 


.892 


.904 


.949 


.881 


.987 










MSHA 






.750 


.882 


.930 


.927 


1.969 


.913 


.950 










USBM 






.658 


.829 


.882 


.936 


.917 


.825 


.920 










U.S. . , 






.634 


.832 


.861 


.897 


1.025 


NA 


NA 










Average . 




.736 


.841 


.890 


.925 


.950 


.874 


.930 










SD . , 






.071 


.043 


.039 


.044 


.050 


.033 


.047 










COV 




. % . . 


9.7 


5.1 


4.4 


4.7 


5.3 


3.8 


5.0 










COV 


Coefficient of variation 
























NA 


Not available. 
























SD 


Standard deviation. 

























Table 5.-Ratio of reported working levels over average working levels 



Participant 




Sept. 12, 


1988 








Sept. 


13, 1988 










14:01 


15:15 


16:09 


9:00 


10:00 


11:00 


12:00 


13:00 


14:00 


15:00 


16:00 


AECB 


1.049 


1.043 


0.993 


NA 


1.005 


0.943 


1.028 


1.031 


1.051 


1.017 


0.963 


ARL 


1.024 


1.024 


1.027 


0.907 


1.014 


1.018 


.835 


1.005 


.997 


.975 


.935 


EML 


NA 


.992 


1.006 


NA 


.961 


.962 


.925 


.956 


.977 


.900 


.972 


EMR 


NA 


NA 


NA 


.990 


1.090 


1.056 


1.151 


1.115 


.997 


1.086 


1.133 


MSHA 


.988 


.977 


.969 


1.103 


1.028 


1.115 


1.133 


.950 


1.059 


1.082 


.996 


USBM 


.939 


.964 


1.006 


NA 


.902 


.932 


.937 


1.005 


1.007 


.985 


1.014 


U.S 


NA 


NA 


NA 


NA 


NA 


.973 


.991 


.940 


.912 


.955 


.987 


SD 


.048 


.033 


.021 


.098 


.064 


.067 


.114 


.061 


.049 


.067 


.064 








Sept 


. 14, 1988 






Av 
ratio 


SD 








9:00 


10:00 


11:00 


12:00 


13:00 


14:01 


14:59 




AECB 


1.139 


1.083 


1.064 


1.099 


1.046 


1.036 


1.041 


1.037 


0.047 




ARL 


1.061 


.989 


1.000 


.979 


.964 


.979 


.941 


.982 


.053 






EML 


.980 


.927 


.933 


.959 


.926 


.988 


.945 


.957 


.029 






EMR 


1.045 


.976 


1.002 


.978 


.999 


1.008 


1.061 


1.046 


.058 






MSHA 


1.019 


1.049 


1.044 


1.003 


1.020 


1.044 


1.022 


1.033 


.051 






USBM 


.894 


.986 


.991 


1.012 


.966 


.944 


.989 


.969 


.038 






U.S 


.862 


.989 


.967 


.970 


1.079 


NA 


NA 


.966 


.054 






SD 


.097 


.051 


.044 


.047 


.053 


.038 


.050 


NAp 


NAp 







NA Not available. 
NAp Not applicable. 
SD Standard deviation. 



Table 6.-Ratio of calculated working levels using reported radon daughter concentrations over reported working levels 



Partici 


pant 






Sept. 12, 


1988 








Sept. 


13, 1988 










14:01 


15:15 


16:09 


9:00 


10:00 


11:00 


12:00 


13:00 


14:00 


15:00 


16:00 


AECB . . . 






1.001 


1.002 


1.001 


NA 


1.001 


1.000 


1.003 


1.002 


1.001 


1.001 


1.001 


ARL 






.996 


.995 


.996 


.994 


.995 


.997 


.996 


.995 


.993 


.994 


.996 


EML 






NA 


.986 


.992 


NA 


.994 


1.002 


.990 


.986 


.989 


.980 


.980 


EMR . . . 






NA 


NA 


NA 


.994 


.996 


.996 


.995 


.994 


.995 


.995 


.994 


MSHA . . 






.967 


.965 


.982 


.987 


.984 


.983 


.984 


.986 


.984 


.984 


.984 


USBM . . 






.999 


.994 


.993 


NA 


.990 


1.002 


1.000 


1.001 


1.000 


1.002 


1.001 








Sept 


. 14, 1988 






Av 
ratio 


SD 








9:00 


10:00 


11:00 


12:00 


13:00 


14:01 


14:59 




AECB . . . 


1.001 


1.001 


1.001 


1.001 


1.001 


1.001 


1.001 


1.001 


0.001 




ARL 






.998 


.997 


.997 


.998 


.998 


NA 


NA 


.996 


.002 






EMI 






.974 


.999 


.987 


.984 


.982 


1.005 


.983 


.988 


.008 






EMR . . . 






.997 


.997 


.997 


.997 


.996 


.996 


.994 


.996 


.001 






MSHA . . 






.984 


.984 


.984 


.983 


.984 


.984 


.984 


.982 


.006 






USBM . . 






1.001 


1.001 


1.001 


1.000 


1.001 


1.002 


1.002 


.999 


.004 






NA Not available. 
























SD Standard deviation. 
























NOTE. 


-WL = 


(RaAx 0.0010287) + 


(RaB x 0.00507745) + 


(RaCx 


0.0037323), 


where RaA, RaB, ; 


and RaC are concentrations in picocuries 


per liter. 





























5 

rr 



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1.3 

1.2 
1.1 
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KEY 

— Radon daughters 

— Radon-222 

— Barometric pressure 

— Relative humidity 




J i L 



I . I 1.0 



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.III! 


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CO 
LJ 

85.0 £ 

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rr 

84.8 w 

o 
rr 
< 



-84.6 







8 10 12 14 16 18 20 22 24 

TIME OF DAY 



Figure 2.-Total radon daughters, radon, barometric pressure, and relative humidity as functions of time, September 12, 1988. 



10 



o 

h- 
< 

rr 

h- 

-z. 

UJ 

o 

-z. 
o 
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1.2 

1.1 
1.0 - 

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.8 

.7 

.6 



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.2 



100 



i — 1 5.5 



KEY 

Radon daughters 

Radon- 222 

Barometric pressure 

Relative humidity 



s 



— ^ -~'^~s 




J i L 



J i L 



85 


90 


>-" 




l- 


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o 




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Z> 
X 


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I.I.I. - 





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CO 
CO 
UJ 

85.0 8: 

o 
rr 



-^84.8 



-84.6 



UJ 

o 
rr 
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m 



TIME OF DAY 



Figure 3.-Total radon daughters, radon, barometric pressure, and relative humidity as functions of time, September 13, 1988. 



11 





1.3 




1.2 


_J 


1 1 


s 




z. 

o 


1.0 


h- 




< 
rr 


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KEY 
Radon daughters 
Radon-222 
Barometric pressure 

Relative humidity 



100 



90 



>- 




h- 


80 


Q 




2 




Z> 
X 


70 


LlI 




> 




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40 



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5.0 

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TIME OF DAY 



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20 22 24 



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85.2 £ 

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CO 
UJ 

85.0 ai 

y 
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84.8 



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rr 
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GO 



84.6 



Figure 4.-Total radon daughters, radon, barometric pressure, and relative humidity as functions of time, September 1 4, 1 988. 



12 



The pump flow rates for the affected three participants 
were adjusted for the probable systematic bias due to 
pump miscalibration (2.5%), and the results are presented 
in table 7. The pump flow rate corrections indicate that 
the maximum average percentage that a participant's 



results were above or below the average concentration was 
only 3.2%. These results appear quite good considering 
these were field measurements and some difference would 
be expected because of measurement of different air and 
statistical counting uncertainties in the methods. 



Table 7.-Ratios of flow-corrected working levels over average working levels 



Participant 



Sept. 12, 1988 



Sept. 13, 1988 



14:01 



15:15 



16:09 



9:00 



10:00 



11:00 



12:00 



13:00 



14:00 



15:00 



16:00 



AECB 

ARL 

EML 

EMR 

MSHA 

USBM 

U.S 

SD 

AECB 

ARL 

EML 

EMR 

MSHA 

USBM 

U.S 

SD 

NA Not available. 
NAp Not applicable. 
SD Standard deviation. 



1.036 

1.037 

NA 

NA 

.976 

.951 

NA 

.043 



9:00 



1.123 

1.073 

.991 

1.031 

1.005 

.904 

.871 

.089 



1.028 

1.034 

1.002 

NA 

.962 

.974 

NA 

.032 



10:00 



1.068 
1.000 

.938 

.963 
1.034 

.997 
1.000 

.043 



0.978 

1.037 

1.015 

NA 

.954 

1.015 

NA 

.033 



NA 
.923 

NA 

.983 

1.094 

NA 

NA 
.087 



0.993 
1.027 

.973 
1.077 
1.015 

.914 
NA 

.055 



0.930 

1.030 

.973 

1.042 

1.100 

.943 

.983 

.060 



1.014 

.845 

.936 

1.136 

1.118 

1.003 
.103 



1.016 
1.016 

.967 
1.099 

.936 
1.016 

.950 

.055 



1.036 

1.008 

.987 

.983 

1.044 

1.018 

.922 

.041 



Sept. 14, 1988 



11:00 



12:00 13:00 



14:01 



14:59 



Av 
ratio 



SD 



1.049 

1.011 

.944 

.988 

1.030 

1.001 

.978 

.035 



1.084 
.990 
.970 
.964 
.989 

1.023 
.981 
.042 



1.032 
.974 
.937 
.985 

1.006 
.977 

1.091 
.050 



1.024 

.992 
1.001 

.996 
1.032 

.956 
NA 

.027 



1.029 

.953 

.958 

1.049 

1.009 

1.002 

NA 

.038 



1.023 
.993 
.968 
1.032 
1.020 
.980 
.977 
NAp 



0.046 
.053 
.029 
.057 
.051 
.038 
.055 
NAp 



1.003 
.986 
.910 
1.071 
1.067 
.996 
.966 
.056 



0.950 
.945 
.983 

1.117 
.982 

1.025 
.998 
.058 



CONCLUSIONS 



The maximum average percentage that a participant's 
results were above or below the average concentration for 
each sample time was only 4.7%. After pump flow rate 
correction for three of the participants, which was nec- 
essary because of an inaccurate pump calibration device, 
this maximum reduced to 3.2%. Systematic biases of 
about 1% and 2%, respectively, in two of the participants' 
results were due to differences in converting individual 
daughter concentrations to working levels. The results of 
the intercomparison appeared to be reasonably good when 



consideration is given to the statistical counting uncer- 
tainties involved and the possibility that the participants 
measured different air. 

The intercomparison was beneficial in identifying mea- 
surement errors due to inaccurate pump calibration and 
different procedures for converting daughter concentra- 
tions to working levels. Additional intercomparisons 
should be periodically performed to assist laboratories in 
identifying measurement errors and helping to assure 
accurate exposure assessments. 



REFERENCES 



1. Knutson, E. O. (ed.). International Intercalibration and 
Intercomparison of Radon, Thoron and Daughters Measuring 
Equipment-Report on Part 1, Radon Measurement. Nucl. Energy 
Agency of Organ, for Econ. Coop, and Dev., and Comm. of Eur. 
Communities, 1986, 62 pp. 

2. Solomon, S. B. (ed.). International Intercalibration and 
Intercomparison of Radon, Thoron and Daughters Measuring 
Equipment-Report on Part II, Radon-Daughter Measurement. Nucl. 
Energy Agency of Organ, for Econ. Coop, and Dev., and Comm. of 
Eur. Communities, 1988, 80 pp. 



3. Droullard, R F., T. H. Davis, E. E. Smith, and R. F. Holub. 
Radiation Hazard Test Facilities at the Denver Research Center. 
BuMines IC 8965, 1984, 22 pp. 

4. Holub, R. F., and P. J. Dallimore. Factors Affecting Radon 
Transport and the Concentration of Radon in Mines. Paper in 
Proceedings of International Conference on Radiation Hazards in 
Mining, ed. by E. Geomez. Soc. Mn. Eng. AIME, 1982, pp. 1022-1028. 

5. Gero, A. J. Evaluation of Four Fast-Response Flow 
Measurement Devices. U.S. Dep. Labor IR 1163, 1988, 8 pp. 



13 



APPENDIX.-PARTICIPANTS 



Australia: 



United States: 



Australian Radiation Laboratory 
Dr. Stephen Solomon 
Lower Plenty Road 
Yallambie, Victoria 
Australia 



Bureau of Mines 

U.S. Department of the Interior 

Dr. Robert F. Holub 

Mr. Ted H. Davis 

Denver Research Center 

Building 20, 

Denver Federal Center 

Denver, CO 80225 

U.SA 



Canada: 



Atomic Energy Control Board 
Ms. Georgena MacDonald 
P.O. Box 1046 
Ottawa, Ontario 
Canada, KIP 5S9 



Environmental Measurements Laboratory 
U.S. Department of Energy 

Dr. Earl O. Knutson 

Dr. Keng Wu Tu 

376 Hudson Street 

New York, NY 10014 

U.SA. 



Department of Energy, Mines, and Resources 
CANMET 

Dr. Jaime Bigu 

P.O. Box 100 

Elliott Lake, Ontario 

Canada, P5A 2J6 



Mine Safety and Health Administration 
U.S. Department of Labor 

Mr. Wade E. Cooper, P.E. 

P.O. Box 25367 

Denver Federal Center 

Denver, CO 80225 

U.SA. 



Europe: 

University of Salzburg 
Dr. Friedrich Steinhausler 
Division of Biophysics 
Hellbrunnerstr. 34 
A-5020 Salzburg 
Austria 



INT.BU.OF MINES,PGH.,PA 29169 



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